Structural Damage Caused
by Water Intrusion:
is the arch-enemy of mortar, capable of damaging it severely in
three significant ways:
By leaching lime:
Water draws lime out of mortar, resulting in mortar increasingly porous and unstable.
By chemically reacting with creosote: Uncapped
chimneys, cracked crowns, deteriorating mortar and bad flashing allow water into a flue.
The water chemically reacts with
creosote to form a highly corrosive acid that begins to
crumble cement bonds from the inside, making a chimney increasingly structurally unstable.
Through frost-wedging: Water expands
7% by volume when it is frozen.
If a freeze should occur while porous
mortar and brick are water-logged, it can generate enough force to
literally pry open cracks in the mortar and push (or “spall”) bricks away
from the chimney, and onto the roof & ground below.
Frost-wedging can literally pry apart entire sections of the chimney:
When bricks and mortar are involved, this can mean sections weighing hundreds of pounds:
concern, because mortar is necessary to support the thousands of
pounds of bricks unstable sandy
mortar can risk a structural chimney collapse:
How Do I Make My
are many possible entry points for rain water to make its way into a
chimney, so keeping a chimney water-tight requires the concerted
“teamwork” of various components, all of which work together and
depend upon each other to work properly.
following are the five primary ways to prevent water intrusion into a
Install a Chimney Cap:
caps prevent direct water penetration into
the chimney flue.
This is the most
fundamental thing one can do to protect a chimney from water damage.
chimney caps also incorporate a metal mesh that acts as both an animal guard (preventing birds and small mammals from
entering and nesting in the chimney, and preventing sparks and embers carried up by draft during a fire from
landing on the roof).
Build (or repair) a chimney crown: The crown covers the top of the chimney by setting a
water-proof slope that redirects water that runs
off the rain cap.
proper chimney crown should be mixed with an elastic (& water resistant) compound such as MascoSeal ®.
3. Flashing: “Flashing” is a metal
barrier that prevents water from entering the chimney where it meets the roof.
flashing is actually composed of two elements: “base” flashing
and “counter” flashing.
The base flashing is an “L”-shaped
piece of metal that presses up tightly against the corner where the
roof and chimney meet. The
counter-flashing is embedded directly into the chimney right above
the base flashing, and is bent downward over base flashing--acting
like a mini-umbrella, it directs rain water away from the chimney.
If the mortar binding the bricks together is weak and porous, it will literally wick water into the flue (through the process called
“adhesion”), where it can do serious damage.
This problem can be resolved with
tuck-pointing (using a high-speed grinder to grind away 1/2” to 1”
into the and mortar separating the bricks, then refilling it with
fresh mortar that will resist water and add significantly more
Water Seal: Even
carefully-struck mortar bonds and high-quality brick are inherently
For this reason, we use a professional specialized
polymer spray-on compound (Siloxane®) to make the brick and
mortar on the outside of your chimney water resistant. Think of it
as the equivalent of Scotch-Guarding® the outside of your
unlike paint, which accelerates mortar damage by trapping water that
has already entered the chimney, our commercial-grade sealant is
vapor permeable, meaning that any moisture coming from the inside of
the chimney will be able to get out (but not back in).
seal application comes with a 10-year warranty.
Give Yourself Peace of Mind.
Schedule a Free Estimate Today:
(503) 775 - 3085
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